The left back signed by Iain Dowie has signed a three and a half year deal at Loftus Road with the Sky Blues receiving a fee believed to have been £300,000.
He made 20 starts for City in the league after a £650,000 move from Crystal Palace. He also had one substitute appearance, three league cup outings and two FA Cup games.
Borrowdale played a number of times for City Reserves and scored the goal of the season against Shrewsbury Town where he raced from deep inside his own half before lashing the ball into the net from thirty yards.
He had not made a first team appearance this season and had been on loan at QPR since November.
All at Covsupport wish him well